射频仿真系统中球面复合阵列近场效应研究

Study on the near-field effect of spherical composite antenna arrays in the radio frequency simulation system

射频复合阵列近场效应影响目标信号的测角精度,为了修正目标信号测角精度,提出一种方法:联合全波算法和一致性几何绕射理论,精确计算给定子阵(三元组)天线在周围同频、异频天线单元存在的环境中发射时,接收天线位置处(通常位于发射三元组的辐射近场)的电场分布;基于此电场相位分布,应用相位梯度法求出三元组辐射场的等效相位中心,并计算与基于幅度重心公式所得等效波源点位置的偏差,使用推导的辅助修正公式获得修正后的三元组各单元输入功率.计算实例表明:经修正后微波/毫米波三元组约束的三角形区域内最大垂直(俯仰)方向测角精度由1.50/2.37mrad降低至0.06/0.06 mrad.

The angular accuracy of target signal is affected by the near-field effect in the radio frequency composite array.This paper presents a new method to solve the problem.The radiation electric field distribution of a three-element sub-array located on the spherical composite antenna arrays at the receiving antenna location,which is usually located in the radiating near-field region,is precisely calculated by an hybrid technique of the full-wave algorithm and uniform geometrical theory of diffraction(UTD),in the case of the three-element array surrounded with its nearby elements working at same and different frequencies.The equivalent phase center of the three-element array is then obtained by the phase gradient algorithm(PGA)based on its phase distribution.The deviation of the equivalent phase center with that derives from the amplitude gravity center equation is calculated,which is used to find the corrected input power for each element antenna of the three-element array.The simulation results for a real composite antenna array system show that the maximum angular accuracy of pitching direction is corrected from1.50/2.37milliradian to0.06/0.06milliradian on the microwave three-element antenna and millimeter wave three-element antenna.